PERMFILE130419

• Permit No: C1980007A
• IBM Index Class Name: Permit File
• Doc Date: 4/8/2005
• Section_Exhibit Name: Exhibit 60C Subsidence Evaluation 2004 Geological Hazard Field Observations for the WFLA
• Media Type: D
• Archive: Yes

TABLE OF GONTENTS
Paae
1.0 SUMMARY OF MAJOR FINDINGS ................................................................................1
2.0 OVERVIEW OF FIELD GEOLOGIC STUDIES DURING JULY 12 -16, 2004 ................3
3.0 INTRODUCTION .................................................
............................ . .. 4
4.0 MINING METHOD ...........................................................................................................5
5.0 GEOLOGIC FACTORS INFLUENCING SUBSIDENCE ..................................................6
6.0 FIELD RECOGNITION OF SUBSIDENCE AND NON-SUBSIDENCE FEATURES IN
THE WEST ELK MINE AREA .........................................................................................7
6.1 Subsidence Cracks and Compression Features .................................................................7
6.2 Desiccation Cracks ..............................................................................................................8
6.3 Pseudo Subsidence Cracks (Gravity-Induced Tension Cracks) .........................................8
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7.0 SUBSIDENCE PREDICTION BASED ON PAST LONGWALL MINING .......................10
7.1 Vertical and Horizontal Displacement, Tilt, Curvature, and Horizontal Strain ...................10
7.1.1 Maximum Vertical Displacement (Subsidence) .................................................13
7.1.2 Maximum Tilt .....................................................................................................14
7.1.3 Maximum Horizontal Strain ................................................................................14
7.2 Maximum Projected Depths of Surface Cracks ................................................................15
8.0 FIELD OBSERVATIONS AND EVALUATIONS AT INDIVIDUAL LOCATIONS FROM
JULY 12 THROUGH JULY 16 ......................................................................................17
8.1 Location 1 ..........................................................................................................................19
8.2 Location 2 ..........................................................................................................................20
8.3 Location 3 ..........................................................................................................................21
8.4 Location 4 ..........................................................................................................................23
8.5 Location 5 ..........................................................................................................................25
9.0 CONCLUSIONS ............................................................................................................27